TWiki Templates

Definition of the templates used to render all HTML pages displayed in TWiki

Overview

The new modular template system offers flexible, easy control over the layout of all TWiki pages. The master template approach groups parts that are shared by several templates - like headers and footers - in a common file. Special variables allow individual layouts to include parts from a master template - variables are mixed with regular HTML markup for template-specific content. Templates are used to define page layout, and also to supply default content for new pages.

Major changes from the previous template system

Where the old templates were each complete HTML documents, the new templates are defined using variables to include template parts from a master file. You can now change one instance of a common element to update all occurrences; previously, every affected template had to be updated. This simplifies the conversion of templates into XHTML format, and provides a more versatile solution for templates and for TWikiSkins. The new system:

separates a set of common template parts into a base template that is included by all of the related templates;

defines common variables, like a standard separator (ex: "|"), in the base template;

defines variable text in the individual templates and passes it back to the base template.

How Template Variables Work

All template preprocessing is done in &TWiki::Store::readTemplate() so that the caller simply gets an expanded template file (the same as before).

Directives are of the form %TMPL:<key>% and %TMPL:<key>{"attr"}%.

Directives:

%TMPL:INCLUDE{"file"}%: Includes a template file. The template directory of the current web is searched first, then the templates root (twiki/templates).

%TMPL:DEF{"var"}%: Define a variable. Text between this and the END directive is not returned, but put into a hash for later use.

%TMPL:END%: Ends variable definition.

%TMPL:P{"var"}%: Prints a previously defined variable.

Variables live in a global name space: there is no parameter passing.

Two-pass processing lets you use a variable before or after declaring it.

Templates and TWikiSkins work transparently and interchangeably. For example, you can create a skin that overloads only the twiki.tmpl master template, like twiki.print.tmpl, that redefines the header and footer.

Use of template directives is optional: templates work without them.

NOTE: Template directives work only for templates: they do not get processed in topic text.

Types of Template

There are three types of template:

Master Template: Stores common parts; included by other templates

HTML Page Templates: Defines the layout of DENX pages

Template Topics: Defines default text when you create a new topic

Master Templates

Common parts, appearing in two or more templates, can be defined in a master template and then shared by others: twiki.tmpl is the default master template.

Legend:• script refers to the script name, e.g view, edit• Script refers to the same, but with the first character capitalized, e.g View• skin refers to the skin name, e.g dragon, pattern• Skin refers to the same, but with the first character capitalized, e.g Dragon• %WEB% refers to the current web

Additionally (and primarily for use in %TMPL:INCLUDE{}%) the template name may be a wiki topic name, specified as Web.Topic, in which case the search is:

All template topics are located in the TWiki web. The WebTopicEditTemplate can be overloaded. When you create a new topic, TWiki locates a topic to use as a content template according to the following search order:

A topic name specified by the templatetopic CGI parameter.

WebTopicEditTemplate in the current web

WebTopicEditTemplate in the TWiki web

Edit Template Topics and Variable Expansion

The following variables get expanded when a user creates a new topic based on a template topic:

A no-operation variable that gets removed. Useful to prevent a SEARCH from hitting an edit template topic; also useful to escape a variable like %URLPARAM%NOP%{...}%

%NOP{ ... }%

A no-operation text that gets removed. Useful to write-protect an edit template topic, but not the topics based this template topic. See notes below. Example:%NOP{ * Set ALLOWTOPICCHANGE = Main.TWikiAdminGroup }%

Notes:

Unlike other variables, %NOP{ ... }% can span multiple lines.

The scan for the closing }% pattern is "non-greedy", that is, it stops at the first occurance. That means, you need to escape variables with parameters located inside %NOP{ ... }%: Insert a %NOP% between } and %. Silly example: %NOP{ %GMTIME{"$year"}%NOP%% }%.

All other variables are unchanged, e.g. are carried over "as is" into the new topic.

Template Topics in Action

Here is an example for creating new topics based on a specific template topic:

New example topic:
(date format is YYYYxMMxDD)

The above form asks for a topic name. A hidden input tag named templatetopic specifies ExampleTopicTemplate as the template topic to use. Here is the HTML source of the form:

If set, TWiki will complain if a topic of the same name already exists

templatetopic

The name of the template topic, e.g. topic used to copy the initial content

topicparent

Sets the parent topic

TopicClassification

Assuming the template topic has a form with a field called "TopicClassification", it will set the value of the field

contenttype

Optional parameter that defines the application type to write into the CGI header. Defaults to text/html. May be used to invoke alternative client applications

anyname

Any parameter can passed to the new topic; if the template topic contains %URLPARAM{"anyname"}%, it will be replaced by its value

TIP: You can use the %WIKIUSERNAME% and %DATE% variables in your topic templates to include the signature of the person creating a new topic. The variables are expanded into fixed text when a new topic is created. The standard signature is: -- %WIKIUSERNAME% - %DATE%

Templates by Example

Attached is an example of an oops based template oopsbase.tmpl and an example oops dialog oopstest.tmpl based on the base template. %A% NOTE: This isn't the release version, just a quick, simple demo.

Base template oopsbase.tmpl

The first line declares a delimiter variable called "sep", used to separate multiple link items. The variable can be called anywhere by writing %TMPL:P{"sep"}%

Sample screen shot of oopstest.tmpl

With URL: .../bin/oops/Sandbox/TestTopic2?template=oopstest&param1=WebHome&param2=WebNotify

Known Issues

A drawback of referring to a master template is that you can only test a template from within TWiki, where the include variables are resolved. In the previous system, each template was a structurally complete HTML document with a .tmpl filename extension - it contained unresolved %VARIABLES%, but could still be previewed directly in a browser.